From: Jakub Jelinek <jakub@redhat.com>
To: Mark Wielaard <mark@klomp.org>
Cc: dwz@sourceware.org
Subject: Re: [PATCH] Don't handle blocks as exprlocs for DWARF version 4 or higher.
Date: Thu, 18 Feb 2021 15:09:47 +0100 [thread overview]
Message-ID: <20210218140947.GG4020736@tucnak> (raw)
In-Reply-To: <3fd1ebde0c9e1b8cbe09ea858a3e0f0a84af44b4.camel@klomp.org>
On Thu, Feb 18, 2021 at 02:40:36PM +0100, Mark Wielaard wrote:
> On Sat, 2021-02-13 at 23:46 +0100, Mark Wielaard wrote:
> > Since DWARF version 4 blocks just contain bytes, trying to interpret
> > them as exprlocs will most likely fail.
> >
> > * dwz.c (add_locexpr_dummy_dies): Only handle block as exprloc
> > for cu_version < 4.
> > (checksum_die): Likewise.
> > (write_die): Likewise.
> >
> > https://sourceware.org/bugzilla/show_bug.cgi?id=26987
>
> Ping. Any comments?
Doing some GCC archeology if it is safe, I think it principially ok, but I'd
like slightly different patch, see below.
While -gdwarf-4 support has been added in
https://gcc.gnu.org/r0-96109-g15b3fbeb7e97f2ca3731881bf3a0f899ec56ebbf
during GCC 4.5 development, it was still emitting DWARF 3 .debug_info
headers and not using DW_FORM_exprloc.
DW_FORM_exprloc came with:
https://gcc.gnu.org/r0-99103-g290d8971e6e3b784a88b5c4b6b91b8d77552cb3a
and DWARF version .debug_info header changed from 3 to 4 for -gdwarf-4
a day after that:
https://gcc.gnu.org/r0-99139-g2f43d500a6769e563fb8f645e7530c2f144d7023
> > +++ b/dwz.c
> > @@ -2913,43 +2913,44 @@ add_locexpr_dummy_dies (DSO *dso, dw_cu_ref
> > cu, dw_die_ref die,
> > if (form == DW_FORM_block1)
> > {
> > /* Old DWARF uses blocks instead of exprlocs. */
Instead of reindenting everything, can't you simply change
- if (form == DW_FORM_block1)
+ if (form == DW_FORM_block1 && cu->cu_version < 4)
> > if (form == DW_FORM_block1)
And likewise here:
- if (form == DW_FORM_block1)
+ if (form == DW_FORM_block1 && cu->cu_version < 4)
> > @@ -12392,7 +12394,7 @@ write_die (unsigned char *ptr, dw_cu_ref cu,
> > dw_die_ref die,
> > ptr += inptr - orig_ptr;
> >
> > /* Old DWARF uses blocks instead of exprlocs. */
> > - if (form == DW_FORM_block1)
> > + if (form == DW_FORM_block1 && cu->cu_version < 4)
Like you've done it here?
> > switch (reft->attr[i].attr)
> > {
> > case DW_AT_frame_base:
Jakub
next prev parent reply other threads:[~2021-02-18 14:09 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-13 22:46 Mark Wielaard
2021-02-18 13:40 ` Mark Wielaard
2021-02-18 14:09 ` Jakub Jelinek [this message]
2021-02-18 16:18 ` Mark Wielaard
2021-02-18 16:59 ` Jakub Jelinek
2021-02-18 17:32 ` Jakub Jelinek
2021-02-18 20:01 ` Mark Wielaard
2021-02-18 20:06 ` Jakub Jelinek
2021-02-18 21:17 ` Mark Wielaard
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